TP53 and Familial adenomatous polyposis: Given that the tissues harboring the aging-associated gene expression alterations (the tissues composed of FPlo cells) are histologically and functionally normal, these alterations might occur even before the formation of aberrant crypt foci, the earliest preadenomatous regions that are distinguishable from the normal tissues by their abnormal morphology and usually harbor genetic mutations in KRAS and/or p53 in the sporadic cases and in APC in the FAP patient cases [50, 51].